This is called the Michigan, so named because it is a staple workout done by the University of Michigan. It is a little complicated.
1200 @ 10k pace
2-3 min jog rest to the start of a mostly grassy mile
1 Mile @ LT over hills and fields, this is by feel and should be comfortably uncomfortable you will return to the track
2-3 min jog rest
800 @ 5k pace
2-3 min jog rest
1 Mile @ LT (grassy)
2-3 min jog rest
400 @ as fast as you can
We’ll map out a reasonable loop for the mile @LT during our warm up.
(FYI there are other versions that start with a longer first interval 1600, 1200, 800, 400 etc)
Summary (2 min easy walk jog between each)
1600 @ 10K -Start here if you want a challenge and are running at least 45 miles a week
1 mile @ LT (grass)
1200 @ 10K – everyone else start here
1 mile @ LT (grass)
800 @ 5k
1 mile @ LT (grass)
400 @ all out